The objectives of this contract are to determine the potential toxicity and carcinogenicity of 6 chemicals via the oral route to F344 rats and B6C3F1 mice. The project involves prechronic and/or chronic studies as follows: Sodium chlorate involves 21-day and 2-year studies via dosed water. Special studies in the 21-day study include cell proliferation and clinical laboratory studies. Dibromoacetic acid involves 14-day, 90-day and 2-year studies via dosed water. Special studies in the 90-day study include cell proliferation, clinical laboratory studies, and SMVCE. MX involves 14-day, 90-day and 2-year studies via dosed water. Special studies in the 90-day study include clinical laboratory studies and SMVCE. Bromodichloromethane involves 21-day and 2-year studies via dosed water. Special studies in the 21-day study include cell proliferation and clinical laboratory studies. 2-Methylimidazole involves 2-year studies via dosed feed, with special studies including thyroid hormones and UDP-GT. 4-Methylimidazole involves 2-year studies via dosed feed, with special studies including thyroid hormones and UDP-GT.